Crib mobiles provide for rotation of decorative items or toys that are suspended above a crib in sight of an infant occupying the crib. These devices typically have a support arm that is connected to a crib by a means such as clamping, a motor-driven rotatable structure supported by the arm, the rotatable structure including means for securing the toys or other objects for rotation in a desired path. Other necessary features have included an electrical power supply such as a battery and a switch for turning the device on and off.
Various arrangements for operation of motor-driven mobiles placed over an infant's crib are disclosed in prior art patents. Many of the prior devices, as exemplified by U.S. Pat. No. 3,919,795, require the attention of another person to turn them on and off. Crib mobiles that may have their motion initiated automatically in response to sound produced by an infant are disclosed is U.S. Pat. Nos. 4,207,696 and 4,640,034. The former of these patents discloses a microphone-activated mobile system that includes energy storing means and a time delay that prevents reactivation during a predetermined period. The latter patent discloses a mode of operation in which motion of the mobile and playing of sound such as a soothing voice or music over a speaker are initiated by detection of sounds that exceed a threshold value.
While sound-activated mobiles provide an educational experience to the infant to the extent that he or she is able to exercise some control over part of the environment, a possibility exists that the baby would misinterpret the control function and decide for itself that crying or loud angry sounds are required to make the mobile operate. Sound activation also would interfere with operation of a cassette or other device to play music or recorded sounds, requiring inclusion of means for establishing the duration of time that such device stays on after having been activated in response to sensed sound. During such period, the baby loses control and the motion of the mobile does not relate directly to the activity level of the baby, thus confusing the educational experience.
Prior mobiles designed to directly attach to a crib present another disadvantage in that batteries would be mandated for safe operation, and the baby would become frustrated when the batteries run down. Clamping and support hardware for this type of mobile also tends to encumber the crib area and interfere with access to the crib.